Positioning glue and its application

Abstract

The application provides a positioning adhesive and application thereof. The positioning adhesive comprises a glue film substrate layer, a glue layer and a release film layer which are stacked in sequence; the glue film substrate layer comprises a base resin and a cross-linking monomer, and the base resin comprises a first ethylene-vinyl acetate copolymer and a polyolefin elastomer; the glue layer comprises a main body resin, and the main body resin comprises a second ethylene-vinyl acetate copolymer. The positioning adhesive of the application can be fully melted and fused with the glue film at the assembly laminating temperature, and the solid-solid interface formed due to the mismatch of the thermal expansion coefficients or the interface incompatibility of the traditional non-meltable substrate during the lamination process is completely eliminated, so that the generation and accumulation of bubbles are inhibited. The chemical compatibility and cross-linking synergy of the glue layer and the glue film substrate layer strengthen the interlayer bonding strength, avoid the interface delamination problem caused by long-term thermal cycling or damp-heat aging after lamination, and solve the problems of interface delamination and bubble residue caused by poor material compatibility during the lamination process in the assembly packaging process.

Description

Technical Field

[0001] This invention relates to the field of positioning adhesive technology, and more specifically, to a positioning adhesive and its application. Background Technology

[0002] In existing technologies, PET's excellent high-temperature resistance ensures no deformation during lamination; its high mechanical strength prevents cell displacement after lamination; and its high weather resistance allows it to withstand long-term UV radiation and temperature / humidity cycling. However, PET's melting point is >200 degrees Celsius, higher than the module lamination temperature, leading to the generation of numerous bubbles during lamination and severely affecting the module's appearance. Furthermore, PET and photovoltaic encapsulation films (EVA / POE) are incompatible systems. After lamination, the PET substrate remains permanently inside the module, forming a solid-solid interface that can last up to 25 years. Under damp-heat aging and thermal cycling, this interface is one of the core causes of edge delamination and abnormal PID degradation in double-glass modules.

[0003] Patents using adhesive film as the substrate for positioning tapes are rare, lacking a systematic patent portfolio. Chinese patent application CN103555217A describes an EVA positioning tape for crystalline silicon solar cell modules. During module lamination, the adhesive film substrate fuses seamlessly with the EVA film, preventing issues like bubbles and delamination. However, this patent overlooks the problem of substrate melting leading to tape structural damage and rendering it ineffective in preventing cell misalignment, thus drawing some controversy.

[0004] Therefore, developing a positioning adhesive to overcome the problems of interface delamination and bubble residue caused by poor material compatibility during the lamination process of component encapsulation in existing technologies, as well as the positioning offset caused by component deformation, has become one of the key issues that the industry urgently needs to solve. Summary of the Invention

[0005] The main objective of this invention is to provide a positioning adhesive and its application to solve the problems of interface delamination and bubble residue caused by poor material compatibility during the lamination process of component encapsulation in the prior art, as well as the positioning displacement caused by component deformation.

[0006] To achieve the above objectives, according to one aspect of the present invention, a positioning adhesive is provided, comprising a film substrate layer, an adhesive layer, and a release film layer stacked sequentially; wherein the film substrate layer comprises a matrix resin and a crosslinking monomer, the matrix resin comprising a first ethylene-vinyl acetate copolymer and a polyolefin elastomer; the adhesive layer comprises a host resin, the host resin comprising a second ethylene-vinyl acetate copolymer; and the film substrate layer is a pre-crosslinked film.

[0007] Furthermore, the VA content of the first ethylene-vinyl acetate copolymer is 28% to 33%; and / or, the mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer is (3:1) to (2:1).

[0008] Further, the pre-crosslinking degree of the above-mentioned adhesive film substrate layer is <70%, preferably 30%~65%, more preferably 50%~65%; and / or, the thickness of the adhesive film substrate layer is 80~120μm; and / or, the basis weight of the adhesive film substrate layer is 100~200g / m³. 2 .

[0009] Further, by weight, the above-mentioned adhesive film substrate layer comprises: 100-130 parts of matrix resin, 2-8 parts of crosslinking monomer, 0.8-2.5 parts of thermal initiator, 0.3-1.5 parts of photoinitiator, 2-2.5 parts of tackifying resin, and 0.3-1.2 parts of antioxidant; preferably, the crosslinking monomer is selected from any one of trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, and diallyl phthalate. Or multiple; and / or, the thermal initiator is selected from any one or more of tert-butyl peroxypentanoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, and di-tert-pentyl peroxide; and / or, the photoinitiator is selected from any one or more of photoinitiator 184, photoinitiator TPO, BDK benzoin dimethyl ether, phenyl ketone ITX, and acylphosphine oxide 819; and / or, the tackifying resin is selected from a first alkyl group. Oxykrylamide oligomers, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, diethylaminomethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethoxymethylvinylsilane, diethoxy The product comprises any one or more of methyl vinyl silane, p-styryltrimethoxysilane, and p-styryltriethoxysilane, wherein the number average molecular weight of the first alkoxysilane oligomer is 300-2000 and the degree of polymerization Xn is 2-20; and / or, the antioxidant is selected from any one or more of light stabilizer 770, antioxidant 1010, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168.

[0010] Furthermore, the VA content of the above-mentioned second ethylene-vinyl acetate copolymer is 28%~33%; and / or, the melt index of the second ethylene-vinyl acetate copolymer at 190°C and 2.16 kg is 15~30 g / 10 min.

[0011] Further, by weight, the above-mentioned adhesive layer comprises: 100-130 parts of a main resin; 0.5-3.0 parts of an initiator; 0.5-5.0 parts of a multifunctional crosslinking monomer; 1.0-8.0 parts of a dialkoxysilane oligomer; 0.2-2.0 parts of a functional additive; and 40-80 parts of an organic solvent; preferably, the initiator is selected from 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, di(4-methylbenzoyl)peroxide, benzoyl peroxide, dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, 4,4-di( The following are selected from one or more of the following: tert-amyl peroxy(butyl)valerate, ethyl 3,3-di(tert-butylperoxy)butyrate, isopropyl tert-butyl peroxycarbonate, 2-ethylhexyl peroxycarbonate, tert-amyl peroxy(2-ethylhexyl)carbonate, and tert-amyl peroxycarbonate; and / or, the multifunctional crosslinking monomer is selected from one or more of 2-divinylbenzene, trimethylolpropane trimethacrylate (TMPTMA), and diallyl disulfide (DADS); and / or, the number average molecular weight of the dialkoxysilane oligomer is 300-2000, and the degree of polymerization Xn is 2-20; and / or, the organic solvent is selected from one or more of ethyl acetate, toluene, and xylene.

[0012] Furthermore, the aforementioned functional additives include antioxidants and light stabilizers, wherein the antioxidants are selected from any one or more of antioxidant 1010, dilauryl thiodipropionate (DLTP), light stabilizer 770, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168; and / or, the light stabilizers are selected from any one or more of hindered amine light stabilizers and benzophenone light stabilizers.

[0013] Furthermore, the release film layer is biaxially oriented PET, the thickness of the release film layer is 75±5μm, and the release force of the release film layer is 3~5 N / 25mm.

[0014] Furthermore, the peel force of the aforementioned positioning adhesive is 2.512~3.589 N / cm; and / or, the cell displacement caused by the positioning adhesive is 0.03~0.07cm; and / or, the light transmittance of the positioning adhesive is 90%~94.3%; and / or, the overflow area ratio of the positioning adhesive is 1.6%~1.85%; and / or, the initial water vapor permeability of the positioning adhesive is 3.13~4.57g / m 2 After aging at 85℃ / 85%RH for 96 hours per day, the water vapor permeability of the positioning adhesive was 4.63~6.99 g / m³. 2 / day.

[0015] According to another aspect of the present invention, an application of the aforementioned positioning adhesive is provided, wherein the aforementioned positioning adhesive is applied to any of the products in laminated glass, photovoltaic modules, and device encapsulation.

[0016] Applying the technical solution of this invention, the positioning adhesive of this application adopts a structure of sequentially stacked adhesive film substrate layer, adhesive layer, and release film layer. First, this application uses an adhesive film with a certain degree of pre-crosslinking as the substrate of the positioning tape. The matrix resin of the adhesive film substrate layer is composed of ethylene-vinyl acetate copolymer (EVA) and polyolefin elastomer (POE), which allows this layer to fully melt at the module lamination temperature and achieve molecular-level fusion with the adhesive film system inside the module. This completely eliminates the solid-solid interface formed during the lamination process of traditional non-meltable substrates due to mismatched coefficients of thermal expansion or interfacial incompatibility, thereby effectively suppressing the generation and accumulation of bubbles and preventing problems such as interface delamination due to aging. At the same time, since the adhesive film substrate layer is a pre-crosslinked film, although the positioning tape "disappears" after lamination, it still ensures that the battery cells hardly shift after lamination, thus achieving the positioning function. Furthermore, the main resin in the adhesive layer is a second ethylene-vinyl acetate copolymer, which exhibits excellent chemical compatibility and crosslinking synergy with the EVA / POE system of the adhesive film substrate layer. This ensures appropriate initial tack, prevents adhesive overflow at high temperatures, and, after lamination, the adhesive layer, substrate layer, and lower adhesive film undergo ternary co-crosslinking during lamination, forming chemical bonds. This significantly improves the interfacial shear strength compared to physical bonding, further enhancing interlayer adhesion and preventing interfacial delamination caused by long-term thermal cycling or damp heat aging after lamination. Finally, a release film is used as an auxiliary agent to solve the problem of insufficient rigidity of the adhesive film-based positioning tape before lamination. In summary, by leveraging the melt compatibility of the material system, positioning and encapsulation are integrated, significantly improving the long-term reliability and encapsulation yield of photovoltaic modules. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A schematic diagram of the positioning adhesive according to the present invention is shown.

[0019] The above figures include the following reference numerals:

[0020] 1. Adhesive film substrate layer; 2. Adhesive layer; 3. Release film layer. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] As analyzed in the background section of this application, the prior art has problems such as interface delamination and bubble residue caused by poor material compatibility during the lamination process of component encapsulation, as well as positioning displacement caused by component deformation. This application provides a positioning adhesive and its application.

[0023] According to a typical embodiment of this application, a positioning adhesive is provided, such as... Figure 1 As shown, the positioning adhesive includes a film substrate layer 1, an adhesive layer 2, and a release film layer 3 stacked sequentially; wherein, the film substrate layer includes a matrix resin and a crosslinking monomer, the matrix resin including a first ethylene-vinyl acetate copolymer and a polyolefin elastomer; the adhesive layer includes a host resin, the host resin including a second ethylene-vinyl acetate copolymer; the film substrate layer is a pre-crosslinked film.

[0024] The positioning adhesive of this application adopts a structure consisting of a substrate layer, an adhesive layer, and a release film layer stacked sequentially. First, this application uses a pre-crosslinked adhesive film as the substrate of the positioning tape. The matrix resin of the substrate layer is composed of ethylene-vinyl acetate copolymer (EVA) and polyolefin elastomer (POE), which allows this layer to fully melt at the module lamination temperature and achieve molecular-level fusion with the adhesive film system inside the module. This completely eliminates the solid-solid interface formed during the lamination process of traditional non-meltable substrates due to mismatched coefficients of thermal expansion or interfacial incompatibility, thereby effectively suppressing the generation and accumulation of bubbles and preventing problems such as interface delamination due to aging. At the same time, since the substrate layer is a pre-crosslinked film, although the positioning tape "disappears" after lamination, it still ensures that the solar cells hardly shift after lamination, thus achieving the positioning function. Furthermore, the main resin in the adhesive layer is a second ethylene-vinyl acetate copolymer, which exhibits excellent chemical compatibility and crosslinking synergy with the EVA / POE system of the adhesive film substrate layer. This ensures appropriate initial tack, prevents adhesive overflow at high temperatures, and, after lamination, the adhesive layer, substrate layer, and lower adhesive film undergo ternary co-crosslinking during lamination, forming chemical bonds. This significantly improves the interfacial shear strength compared to physical bonding, further enhancing interlayer adhesion and preventing interfacial delamination caused by long-term thermal cycling or damp heat aging after lamination. Finally, a release film is used as an auxiliary agent to solve the problem of insufficient rigidity of the adhesive film-based positioning tape before lamination. In summary, by leveraging the melt compatibility of the material system, positioning and encapsulation are integrated, significantly improving the long-term reliability and encapsulation yield of photovoltaic modules.

[0025] In some embodiments of this application, the VA content of the first ethylene-vinyl acetate copolymer is 28% to 33%; and / or, the mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer is (3:1) to (2:1).

[0026] The preferred VA content of the first ethylene-vinyl acetate copolymer within the above range helps promote the melt flow and cross-linking reaction of the substrate layer at the lamination temperature, making it highly compatible with the melt characteristics and cross-linking response of the ethylene-vinyl acetate copolymer in the encapsulating film. This ensures that, while maintaining the initial rigidity of the positioning adhesive for cell positioning, the substrate layer of the encapsulating film softens uniformly and fully integrates into the encapsulation system during hot pressing, reducing interfacial delamination and bubble residue problems caused by poor material compatibility. The preferred mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer within the above range not only helps improve the interfacial adhesion strength between the substrate layer and the encapsulating adhesive but also reduces positioning adhesive residue after lamination, significantly improving the long-term reliability and photoelectric conversion efficiency of the photovoltaic module.

[0027] In some embodiments of this application, the pre-crosslinking degree of the adhesive film substrate layer is <70%, preferably 30%~65%, and more preferably 50%~65%; and / or, the thickness of the adhesive film substrate layer is 80~120μm; and / or, the basis weight of the adhesive film substrate layer is 100~200g / m³. 2 .

[0028] The optimal crosslinking degree of the encapsulant substrate layer within the above range helps it possess sufficient rigidity at room temperature to stably support the positioning of the photovoltaic module, reducing displacement caused by deformation. Simultaneously, at the lamination temperature, the aforementioned crosslinking degree range of the encapsulant substrate layer allows the substrate layer to melt moderately and uniformly penetrate into adjacent adhesive layers, effectively eliminating solid-solid interfaces and reducing residual bubbles and delamination defects. Furthermore, within the aforementioned crosslinking degree range, the substrate layer's elastic modulus ≥50MPa under 25°C storage conditions reduces the risk of cell displacement after lamination, and it maintains sufficient rigidity for positioning at room temperature while remaining flowable at high temperatures. The optimal thickness and basis weight of the encapsulant substrate layer within the above range help it possess the necessary mechanical strength while reducing the risk of cell breakage during lamination due to excessive thickness or weight, as well as the accumulation of residual stress or decreased light transmittance after lamination.

[0029] In some embodiments of this application, the adhesive film substrate layer comprises, by weight, 100-130 parts of a matrix resin, 2-8 parts of a crosslinking monomer, 0.8-2.5 parts of a thermal initiator, 0.3-1.5 parts of a photoinitiator, 2-2.5 parts of a tackifying resin, and 0.3-1.2 parts of an antioxidant; preferably, the crosslinking monomer is selected from trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, and diallyl phthalate. Any one or more of the following; and / or, the thermal initiator is selected from any one or more of tert-butyl peroxypentanoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, and di-tert-pentyl peroxide; and / or, the photoinitiator is selected from any one or more of photoinitiator 184, photoinitiator TPO, BDK benzoin dimethyl ether, phenyl ketone ITX, and acylphosphine oxide 819; and / or, the tackifying resin is selected from... Oligomers of alkoxysilanes, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, diethylaminomethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethoxymethylvinylsilane, di... The product comprises one or more of ethoxymethyl vinylsilane, p-styryltrimethoxysilane, and p-styryltriethoxysilane, wherein the number average molecular weight of the first alkoxysilane oligomer is 300-2000 and the degree of polymerization Xn is 2-20; and / or, the antioxidant is selected from one or more of light stabilizer 770, antioxidant 1010, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168.

[0030] In this application, by optimizing the parameters to be within the above ranges, it helps to ensure the rigid support and dimensional stability of the adhesive film substrate layer during room temperature storage and cutting. Simultaneously, during lamination, the crosslinking reaction rate is synergistically regulated through a dual initiation mechanism of heat and light, reducing positioning misalignment and bubble retention caused by premature or excessively slow crosslinking. Specifically, the preferred number-average molecular weight and degree of polymerization of the first alkoxysilane oligomer within the above ranges facilitate bridging the interface between organic polymers and inorganic materials, significantly improving the interfacial adhesion strength and compatibility between the substrate layer, adhesive layer, and encapsulating film. Furthermore, the preferred type of antioxidant helps to inhibit the oxidative degradation of resin chains under ultraviolet light and high-temperature environments, improving its weather resistance stability during long-term service.

[0031] In some embodiments of this application, the VA content of the second ethylene-vinyl acetate copolymer is 28% to 33%; and / or, the melt index of the second ethylene-vinyl acetate copolymer at 190°C and 2.16 kg is 15 to 30 g / 10 min.

[0032] The preferred VA content of the second ethylene-vinyl acetate copolymer within the above range helps increase the density of polar groups in the molecular chain, thereby enhancing the chemical adsorption and physical entanglement with the EVA / POE substrate layer and glass, and improving adhesion reliability. Simultaneously, the preferred melt flow index helps the adhesive layer maintain controllable flowability when softened by heat, reducing the risk of contamination or uneven thickness caused by excessive flowability, and also reducing problems such as interface bubble residue or insufficient adhesion caused by insufficient flowability. In summary, the preferred parameters help improve the melt flowability and adhesive strength of the adhesive layer at the lamination temperature.

[0033] In some embodiments of this application, the adhesive layer comprises, by weight, 100-130 parts of a main resin; 0.5-3.0 parts of an initiator; 0.5-5.0 parts of a multifunctional crosslinking monomer; 1.0-8.0 parts of a dialkoxysilane oligomer; 0.2-2.0 parts of a functional additive; and 40-80 parts of an organic solvent. Preferably, the initiator is selected from 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, di(4-methylbenzoyl)peroxide, benzoyl peroxide, dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, and 4,4-dimethyl-2,5-bis(tert-butylperoxy)hexane. -Butyl di(tert-amylperoxy)valerate, ethyl 3,3-di(tert-butylperoxy)butyrate, isopropyl tert-butylperoxycarbonate, 2-ethylhexyl tert-butylperoxycarbonate, tert-amyl peroxy-2-ethylhexyl carbonate, and tert-amyl peroxycarbonate; and / or, the multifunctional crosslinking monomer is selected from 2-divinylbenzene, trimethylolpropane trimethacrylate (TMPTMA), and diallyl disulfide (DADS); and / or, the number average molecular weight of the dialkoxysilane oligomer is 300-2000, and the degree of polymerization Xn is 2-20; and / or, the organic solvent is selected from ethyl acetate, toluene, and xylene.

[0034] In this application, by selecting the main resin, initiator within the above-mentioned ranges and types of initiators, the adhesive layer achieves moderate initial tack at room temperature and controllable crosslinking response during high-temperature lamination, effectively reducing the risk of uncontrolled tack or high-temperature adhesive overflow during construction. Simultaneously, the selection of multifunctional crosslinking monomers within the above-mentioned ranges significantly increases the density of the three-dimensional crosslinking network in the adhesive layer, enhancing structural rigidity and thermal stability, and reducing flow deformation issues during lamination. By limiting the number-average molecular weight and degree of polymerization of the dialkoxysilane oligomer, its molecular chain length and functionality are moderate, which helps promote interfacial bridging between the adhesive layer and the adhesive film substrate layer and EVA / POE encapsulation material, forming stable chemical coupling bonds and improving interfacial shear strength and anti-delamination ability. The selection of the aforementioned organic solvents facilitates the adjustment of viscosity, leveling properties, and drying rate during adhesive layer coating, reducing the problems of bubbles or insufficient adhesive during uniform film formation.

[0035] In some embodiments of this application, the aforementioned functional additives include antioxidants and light stabilizers, wherein the antioxidants are selected from any one or more of antioxidant 1010, dilauryl thiodipropionate (DLTP), light stabilizer 770, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168; and / or, the light stabilizers are selected from any one or more of hindered amine light stabilizers and benzophenone light stabilizers.

[0036] Optimizing the types of antioxidants and light stabilizers mentioned above helps to synergistically inhibit the generation of free radicals and chain reactions during thermal oxidation, effectively delaying the degradation of the ethylene-vinyl acetate copolymer backbone under high lamination temperatures. Simultaneously, hindered amine light stabilizers capture UV-induced free radicals and achieve nitric oxide free radical recycling, while benzophenone light stabilizers absorb UV energy and dissipate it as heat, significantly reducing the damage to the molecular structure of the adhesive layer caused by photoaging. The synergistic effect of these two stabilizers enhances the chemical stability of the adhesive layer during long-term service, thereby maintaining its interfacial adhesion strength with the substrate layer and the encapsulating film, reducing the risk of micro-delamination and adhesion failure due to aging, and improving the long-term reliability and encapsulation integrity of photovoltaic modules under harsh environments such as high temperature, high humidity, and strong UV radiation.

[0037] In some embodiments of this application, the release film layer is biaxially oriented PET, the thickness of the release film layer is 75±5μm, and the release force of the release film layer is 3~5 N / 25mm.

[0038] In this application, after preparing the substrate layer and hot melt adhesive layer of the positioning tape using a twin-screw continuous extrusion method, the adhesive layer is coated onto the adhesive film substrate using a wire rod or doctor blade, and a release film is applied to the adhesive layer using a laminating machine. By optimizing the parameters of the release film layer, it provides sufficient mechanical support to the adhesive film substrate layer during storage and cutting, which helps reduce the risk of curling or deformation of the substrate during operation. Simultaneously, after being attached to the edge of the battery string, the release film is immediately peeled off, and the substrate layer adheres in a low-modulus state, reducing the risk of tensile stress and thus minimizing the problem of localized stress concentration and microcracks in the thin-film battery. Therefore, the release film layer reduces both the risk of permanent residue on the PET substrate and the curling and tensile deformation problems of the pure adhesive film substrate. Optimizing the release force range enhances the stable adhesion of the release film during transportation and application, improves the reliability of the peeling operation, and reduces the problem of residual adhesive or damage to the adhesive layer structure.

[0039] The preferred release films can provide tensile modulus support of ≥200MPa.

[0040] In some embodiments of this application, the peel force of the positioning adhesive is 2.512~3.589 N / cm; and / or, the cell displacement of the positioning adhesive is 0.03~0.07cm; and / or, the light transmittance of the positioning adhesive is 90%~94.3%; and / or, the overflow area ratio of the positioning adhesive is 1.6%~1.85%; and / or, the initial water vapor permeability of the positioning adhesive is 3.13~4.57g / m 2 After aging at 85℃ / 85%RH for 96 hours per day, the water vapor permeability of the positioning adhesive was 4.63~6.99 g / m³. 2 / day.

[0041] By limiting the peel force of the aforementioned positioning adhesive within the specified range, it helps to enhance the initial adhesion to the edge of the solar cell, reducing mechanical disturbances during transportation and lamination, while also mitigating the risk of stress damage to the solar cell during peeling due to excessive adhesive force. Limiting the solar cell displacement within the specified range helps to enhance the structural stability of the substrate layer under high-temperature lamination conditions, while suppressing relative displacement of the solar cell due to thermal flow. Limiting the light transmittance within the specified range helps to reduce light scattering defects during the melting and fusion of the substrate layer and the adhesive layer, improving the photoelectric conversion efficiency of the module. Limiting the adhesive overflow area ratio within the specified range helps to control the flow of the adhesive layer at lamination temperatures, reducing the risk of excessive adhesive overflow contaminating the main grid or edge encapsulation areas of the solar cell. Furthermore, limiting the initial and aged moisture permeability within the specified range helps to improve the consistency of its permeation performance with the surrounding EVA / POE film, enhancing the interfacial compatibility of the positioning adhesive with the encapsulation system under long-term humid and hot conditions, and effectively suppressing PID effects and edge delamination risks by reducing the risk of moisture permeation channels formed due to material differences.

[0042] According to another aspect of the present invention, an application of the aforementioned positioning adhesive is provided, wherein the aforementioned positioning adhesive is applied to any of the products in laminated glass, photovoltaic modules, and device encapsulation.

[0043] This application also provides an application of the above-mentioned positioning adhesive in laminated glass, photovoltaic modules, and device encapsulation. The positioning adhesive achieves controllable melting and chemical fusion of the substrate during lamination or hot pressing through the synergistic effect of the pre-crosslinked adhesive film substrate and the adhesive layer. This avoids the problems of interface delamination and damp heat aging failure caused by the residue of traditional rigid substrates (such as PET). At the same time, it relies on the release film to provide mechanical support during the attachment stage to ensure positioning accuracy. After lamination, the adhesive layer and the encapsulation material form a ternary co-crosslinked network, which enhances the interfacial bonding strength and suppresses adhesive overflow. It is suitable for photovoltaic module encapsulation with stringent requirements for long-term reliability and optical performance, as well as electronic device encapsulation with strict requirements for airtightness and weather resistance. It achieves the synchronous dissolution of positioning function and material body, improving the overall durability and appearance consistency of the structure.

[0044] The beneficial effects that this application can achieve will be further illustrated below with reference to embodiments and comparative examples.

[0045] Example 1

[0046] The meltable adhesive film substrate layer was prepared by twin-screw continuous extrusion using a matrix resin (70 parts of ethylene-vinyl acetate copolymer (VA content of 28%), 30 parts of polyolefin elastomer), 2.5 parts of trimethylolpropane trimethacrylate (TMPTMA), 1.0 part of tert-butyl peroxypentanoate, 0.3 parts of photoinitiator TPO, 2.0 parts of alkoxysilane oligomer (number average molecular weight of 800, degree of polymerization Xn=14), and 0.3 parts of light stabilizer 770, with the pre-crosslinking degree of the adhesive film controlled at around 50%.

[0047] The adhesive layer was prepared by continuous twin-screw extrusion using 100 parts of ethylene-vinyl acetate copolymer (VA content 28%, melt index 15 g / 10min at 190℃ and 2.16 kg), 0.5 parts of benzoyl peroxide (BPO), 1.5 parts of trimethylolpropane trimethacrylate (TMPTMA), 3.5 parts of alkoxysilane oligomer (number average molecular weight 800, degree of polymerization Xn=14), 0.3 parts of antioxidant 1010, 0.2 parts of ultraviolet absorber UV-531, and 50 parts of ethyl acetate to obtain the positioning tape.

[0048] The adhesive layer is applied to the adhesive film substrate using a wire rod or scraper, and then a release film is applied to the hot melt adhesive using a laminating machine to finally obtain the positioning tape.

[0049] Example 2

[0050] The difference from Example 1 is that the VA content of the first ethylene-vinyl acetate copolymer is 33%, and the final product is a positioning tape.

[0051] Example 3

[0052] The difference from Example 1 is that the VA content of the first ethylene-vinyl acetate copolymer is 40%, and the final product is a positioning tape.

[0053] Example 4

[0054] The difference from Example 1 is that the mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer is 3:1, resulting in a positioning tape.

[0055] Example 5

[0056] The difference from Example 1 is that the mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer is 4:1, resulting in a positioning tape.

[0057] Example 6

[0058] The difference from Example 1 is that the pre-crosslinking degree of the adhesive film is controlled at 55%, and the final positioning tape is obtained.

[0059] Example 7

[0060] The difference from Example 1 is that the pre-crosslinking degree of the adhesive film is controlled at 65%, and the final positioning tape is obtained.

[0061] Example 8

[0062] The difference from Example 1 is that the VA content of the second ethylene-vinyl acetate copolymer is 33%, and the final product is a positioning tape.

[0063] Example 9

[0064] The difference from Example 1 is that the VA content of the second ethylene-vinyl acetate copolymer is 40%, and the final product is a positioning tape.

[0065] Example 10

[0066] The difference from Example 1 is that the melt index of the second ethylene-vinyl acetate copolymer is 30 g / 10min (190°C, 2.16 kg), and the final product is a positioning tape.

[0067] Example 11

[0068] The difference from Example 1 is that the melt index of the second ethylene-vinyl acetate copolymer is 10 g / 10min (190°C, 2.16 kg), and the final product is a positioning tape.

[0069] Example 12 (Original Comparative Example 3)

[0070] The meltable adhesive film substrate layer was prepared by twin-screw continuous extrusion using a matrix resin (70 parts EVA (VA content of 28%), 30 parts POE), 2.5 parts trimethylolpropane trimethacrylate (TMPTMA), 1.0 part tert-butyl peroxypentanoate, 0.3 parts photoinitiator TPO, 2.0 parts alkoxysilane oligomer (number average molecular weight of 800, degree of polymerization Xn=14), and 0.3 parts light stabilizer 770, with the degree of crosslinking of the adhesive film controlled at 70%.

[0071] The adhesive layer was prepared by continuous twin-screw extrusion using 100 parts of EVA (VA content 28%, melt index 15 g / 10min at 190℃ and 2.16 kg), 0.5 parts of benzoyl peroxide (BPO), 1.5 parts of trimethylolpropane trimethacrylate (TMPTMA), 3.5 parts of alkoxysilane oligomer (number average molecular weight 800, degree of polymerization Xn=14), 0.3 parts of antioxidant 1010, 0.2 parts of ultraviolet absorber UV-531, and 50 parts of ethyl acetate.

[0072] The adhesive layer is applied to the adhesive film substrate using a wire rod or scraper, and then a release film is applied to the hot melt adhesive using a laminating machine to finally obtain the positioning tape.

[0073] Example 13

[0074] The difference from Example 1 is that the pre-crosslinking degree of the adhesive film is controlled at 30%, and the final positioning tape is obtained.

[0075] Comparative Example 1

[0076] The adhesive layer was prepared by continuous twin-screw extrusion using 100 parts EVA, 0.5 parts benzoyl peroxide (BPO), 1.5 parts trimethylolpropane trimethacrylate (TMPTMA), 3.5 parts alkoxysilane oligomer, 0.3 parts antioxidant 1010, 0.2 parts ultraviolet absorber UV-531, and 50 parts ethyl acetate.

[0077] The adhesive layer is applied to the PET substrate using a wire rod or scraper, and then a release film is applied to the hot melt adhesive using a laminating machine to obtain the positioning tape.

[0078] Comparative Example 2

[0079] A meltable adhesive film substrate layer was prepared by continuous twin-screw extrusion using 97.44 parts of EVA resin, 1.5 parts of maleic anhydride, 0.2 parts of silane coupling agent, 0.16 parts of light stabilizer 770, 0.06 parts of dicumyl peroxide (DCP), and 0.3 parts of antioxidant 168. The adhesive film substrate was not cross-linked.

[0080] Take 35 parts of butyl acrylate, 11 parts of methacrylate, 1.5 parts of hydroxyethyl acrylate, 46 parts of ethyl acetate, 0.8 parts of petroleum resin, and 0.35 parts of aromatic amine antioxidant. Prepare the adhesive solution for positioning tape according to the above operation steps. Coat the EVA film substrate with a wire rod, keeping the thickness the same as in the example, and finally obtain the positioning tape.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the matrix resin of the adhesive film substrate layer is only the first ethylene-vinyl acetate copolymer (EVA), and the final product is a positioning tape.

[0083] Comparative Example 4

[0084] The difference from Example 1 is that the matrix resin of the adhesive film substrate layer is only polyolefin elastomer (POE), and the final product is a positioning tape.

[0085] Comparative Example 5

[0086] The difference from Example 1 is that the adhesive film substrate layer is not pre-crosslinked, resulting in a positioning tape.

[0087] The following are some performance testing methods for this positioning tape:

[0088] (1) Peel force test:

[0089] Cut the tape into 1cm wide samples, with at least three strips for each sample. Remove the release film, adhere the adhesive side to the smooth surface of the solar cell, and roll it back and forth three times with a 2kg roller at a speed of approximately 300mm / min to ensure full adhesion between the adhesive side and the solar cell. After adhesion, place the sample in a standard environment for 20 minutes. Clamp the free end of the sample to the upper fixture of a tensile testing machine, with the steel plate clamped in the lower fixture, and peel it 180° at a speed of 300mm / min. Record the peel force and take the arithmetic mean.

[0090] (2) Interface layering rate:

[0091] ① Record the initial state of the components: confirm that there is no visible delamination, bubbles, or delamination, and confirm that the insulation resistance is ≥100MΩ (1500V DC).

[0092] ②Accelerated stress test: Damp heat pretreatment, 85℃ / 85%RH, no voltage, time usually 96h; voltage stress is applied, the module frame is grounded, and the battery circuit is subjected to the maximum system voltage (positive or negative, depending on the module structure); leakage current is monitored every 24h;

[0093] ③Recovery and Inspection: Allow to stand in a dry environment at room temperature for 2-4 hours to eliminate surface condensation; Visual inspection: Record visible abnormalities such as backplate bulges, edge delamination, and bubbles; SAM scan (optional, but recommended): Locate delamination areas ≥1mm² and calculate the total area percentage; Use a water vapor transmission rate tester to measure the water vapor content of these defects. The specific testing steps are as follows:

[0094] The sample, including the layered parts, is cut into a circular shape the size of the test cavity;

[0095] Sample installation: Apply a layer of sealing grease (such as high-vacuum silicone grease) evenly to the edge of the test chamber to ensure airtightness. Place the cut sample flat in the center of the test chamber, gently press to expel air bubbles, and ensure that the edges are completely sealed to prevent edge leakage from causing test failure;

[0096] Set test parameters: Set the temperature to 38±1℃ and the humidity to 90%RH;

[0097] Conduct sample testing and complete data processing.

[0098] (3) Lamination Excess Adhesive: Take the adhesive tape to be tested and cut it into standard strips of 25mm × 100mm, with no less than 3 samples per group. Place the adhesive side of the tape down on the cleaned simulated substrate (glass / backsheet), aligning one end of the tape with the edge of the substrate and extending the other end beyond the substrate (simulating the actual working condition of the tape crossing the edge of the solar cell). Key control: Use a 2kg rubber roller to roll back and forth once at a speed of about 300mm / min to ensure consistent initial adhesion. After lamination and cooling, cut vertically along the centerline of the tape length to expose the interface between the tape and the substrate and the edge of the tape. The cut surface must be flat to avoid secondary deformation of the adhesive. Use a microscope to photograph the edge area of ​​the tape (magnified 10~20 times) to ensure clear imaging of the tape boundary and the excess adhesive area. Take at least 3 different cross-sections for each sample. The degree of adhesive overflow was quantitatively compared using the area percentage of adhesive overflow (S, %) (S = (A / L) × 100%, where A is the projected area of ​​the adhesive overflow region (mm²) and L is the measured length of the tape (mm)).

[0099] (4) Cell displacement: The laminate is prepared with a structure of glass / EVA film / cell / EVA film / glass, wherein the cell consists of two halves. The two cells are fixed with positioning tape to ensure an initial distance of 1cm between them. A line is drawn on the glass to mark the position before lamination. After lamination, the module is allowed to cool to check whether the position of the two cells has changed and by how much.

[0100] (5) Transmittance: The laminated part was prepared with a structure of glass / EVA film / positioning tape substrate film / EVA film / glass. The transmittance of the component was tested using a UV-Vis-NIR spectrophotometer. The operation steps are as follows:

[0101] ① Calibration: Calibration is performed using a standard reflective white plate and black screen;

[0102] ② Sample preparation: The surface must be clean and flat;

[0103] ③ Select parameters: The test wavelength range is 250~1100nm;

[0104] ④ Measure the baseline;

[0105] ⑤ Conduct sample testing.

[0106] (6) Total area of ​​delaminated back panel: Calculate the area of ​​the delaminated back panel. The calculation method is the conventional rectangular area formula. When the area of ​​the delaminated part is irregular, it can be pieced together into a rectangle using the cut-and-paste method before calculation.

[0107] The test results are listed in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0112] The positioning adhesive of this application adopts a structure consisting of a substrate layer, an adhesive layer, and a release film layer stacked sequentially. First, this application uses a pre-crosslinked adhesive film as the substrate of the positioning tape. The matrix resin of the substrate layer is composed of ethylene-vinyl acetate copolymer (EVA) and polyolefin elastomer (POE), which allows this layer to fully melt at the module lamination temperature and achieve molecular-level fusion with the adhesive film system inside the module. This completely eliminates the solid-solid interface formed during the lamination process of traditional non-meltable substrates due to mismatched coefficients of thermal expansion or interfacial incompatibility, thereby effectively suppressing the generation and accumulation of bubbles and preventing problems such as interface delamination due to aging. At the same time, since the substrate layer is a pre-crosslinked film, although the positioning tape "disappears" after lamination, it still ensures that the solar cells hardly shift after lamination, thus achieving the positioning function. Furthermore, the main resin in the adhesive layer is a second ethylene-vinyl acetate copolymer, which exhibits excellent chemical compatibility and crosslinking synergy with the EVA / POE system of the adhesive film substrate layer. This ensures appropriate initial tack, prevents adhesive overflow at high temperatures, and, after lamination, the adhesive layer, substrate layer, and lower adhesive film undergo ternary co-crosslinking during lamination, forming chemical bonds. This significantly improves the interfacial shear strength compared to physical bonding, further enhancing interlayer adhesion and preventing interfacial delamination caused by long-term thermal cycling or damp heat aging after lamination. Finally, a release film is used as an auxiliary agent to solve the problem of insufficient rigidity of the adhesive film-based positioning tape before lamination. In summary, by leveraging the melt compatibility of the material system, positioning and encapsulation are integrated, significantly improving the long-term reliability and encapsulation yield of photovoltaic modules.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A positioning adhesive, characterized in that, The positioning adhesive includes a film substrate layer, an adhesive layer, and a release film layer stacked sequentially. The adhesive film substrate layer comprises a matrix resin and a crosslinking monomer, wherein the matrix resin comprises a first ethylene-vinyl acetate copolymer and a polyolefin elastomer; The adhesive layer includes a host resin, which includes a second ethylene-vinyl acetate copolymer; The substrate layer of the adhesive film is a pre-crosslinked film.

2. The positioning adhesive according to claim 1, characterized in that, The VA content of the first ethylene-vinyl acetate copolymer is 28% to 33%; and / or, the mass ratio of the first ethylene-vinyl acetate copolymer to the polyolefin elastomer is (3:1) to (2:1).

3. The positioning adhesive according to claim 1 or 2, characterized in that, The pre-crosslinking degree of the adhesive film substrate layer is <70%, preferably 30%~65%, and more preferably 50%~65%; and / or, the thickness of the adhesive film substrate layer is 80~120μm; and / or, the basis weight of the adhesive film substrate layer is 100~200g / m³. 2 .

4. The positioning adhesive according to any one of claims 1 to 3, characterized in that, The adhesive film substrate layer comprises, by weight parts: 100-130 parts of the matrix resin; 2 to 8 parts of the crosslinking monomer; 0.8~2.5 parts of thermal initiator; 0.3~1.5 parts of photoinitiator; 2 to 2.5 parts of tackifying resin; 0.3 to 1.2 parts of antioxidant; Preferably, the crosslinking monomer is selected from any one or more of trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl cyanurate, and diallyl phthalate; And / or, the thermal initiator is selected from any one or more of tert-butyl peroxypentanoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, and di-tert-pentyl peroxide; And / or, the photoinitiator is selected from any one or more of photoinitiator 184, photoinitiator TPO, BDK benzoin dimethyl ether, phenyl ketone ITX, and acylphosphine oxide 819; And / or, the tackifying resin is selected from any one or more of the following: first alkoxysilane oligomer, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, diethylaminomethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, p-styryltrimethoxysilane, and p-styryltriethoxysilane, wherein the number average molecular weight of the first alkoxysilane oligomer is 300-2000, and the degree of polymerization Xn is 2-20; And / or, the antioxidant is selected from any one or more of light stabilizer 770, antioxidant 1010, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168.

5. The positioning adhesive according to any one of claims 1 to 4, characterized in that, The VA content of the second ethylene-vinyl acetate copolymer is 28%~33%; and / or, the melt index of the second ethylene-vinyl acetate copolymer at 190°C and 2.16 kg is 15~30 g / 10 min.

6. The positioning adhesive according to any one of claims 1 to 5, characterized in that, The adhesive layer comprises, by weight parts: 100-130 parts of the main resin; 0.5 to 3.0 parts of initiator; 0.5 to 5.0 parts of multifunctional crosslinked monomer; 1.0 to 8.0 parts of dialkoxysilane oligomers; 0.2~2.0 parts of functional additives; 40-80 parts of organic solvent; Preferably, the initiator is selected from any one or more of 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, di(4-methylbenzoyl)peroxide, benzoyl peroxide, dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxide-3,5,5-trimethylhexanoate, 4,4-di(tert-pentylperoxy)valerate, ethyl 3,3-di(tert-butylperoxy)butanoate, tert-butyl peroxycarbonate isopropyl, tert-butyl peroxycarbonate-2-ethylhexyl, tert-ethylhexyl peroxycarbonate-tert-pentyl, and tert-pentyl peroxycarbonate. And / or, the multifunctional crosslinking monomer is selected from any one or more of 2-divinylbenzene, trimethylolpropane trimethacrylate (TMPTMA), and diallyl disulfide (DADS); And / or, the number average molecular weight of the second alkoxysilane oligomer is 300~2000, and the degree of polymerization Xn=2~20; And / or, the organic solvent is selected from any one or more of ethyl acetate, toluene, and xylene.

7. The positioning adhesive according to claim 6, characterized in that, The functional additives include antioxidants and light stabilizers, wherein the antioxidants are selected from any one or more of antioxidant 1010, dilauryl thiodipropionate (DLTP), light stabilizer 770, hindered phenolic antioxidant 1076, hindered phenolic antioxidant 1098, hindered phenolic antioxidant 3114, and phosphite 168; and / or, the light stabilizers are selected from any one or more of hindered amine light stabilizers and benzophenone light stabilizers.

8. The positioning adhesive according to any one of claims 1 to 7, characterized in that, The release film is biaxially oriented PET, the thickness of the release film is 75±5μm, and the release force of the release film is 3~5 N / 25mm.

9. The positioning adhesive according to any one of claims 1 to 8, characterized in that, The peel force of the positioning adhesive is 2.512~3.589 N / cm; and / or, the cell displacement caused by the positioning adhesive is 0.03~0.07cm; and / or, the light transmittance of the positioning adhesive is 90%~94.3%; and / or, the overflow area ratio of the positioning adhesive is 1.6%~1.85%; and / or, the initial water vapor permeability of the positioning adhesive is 3.13~4.57g / m 2 After aging at 85℃ / 85%RH for 96 hours per day, the water vapor permeability of the positioning adhesive is 4.63~6.99 g / m³. 2 / day.

10. An application of the positioning adhesive according to any one of claims 1 to 9, characterized in that, The positioning adhesive is applied to any of the products used in laminated glass, photovoltaic modules, and device encapsulation.

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